I have taken 6 cruises and have these suggestions:
#1
Coud I get one room for the 3 of us?
Yes....you can get a room for the 3 of you.

#2
Would the cost (pp) be less if there are 3 in a room?
Your first two passengers pay full fare. #3 or #4 get a discount in the same room.

#3
Mexico or Hawaii? Which is the more popular cruise (if any)?
Neither...do the Carribean.
#4
What is the VERY CHEAPEST way to book a cruise?
(Cruise line, travel agent, American Express, AAA, etc.)
Try www.skyauction.com. Getting a discount is difficult. I tried.

#5
What cruise line is the most "family friendly" (besides Disney)?
I liked Princess. My kids did not like Carnival. Neither did the adults.

#6
Would it be safe to get off the ship in the Mexican Riviera with just myself and my two ]
daughters?
Not sure about that one.

#7
What do most people prefer, Ocean View or Inside Cabin (no view)?
Get a balcony. Inside makes you feel claustophobic. It's nice to be able to open the window and step out. Some cruise lines offer specials on their balconies.
PB

1. Yes, you can fit comfortably in 1 room.
2. The first 2 people pay full fare, the 3rd one would be discounted.
3. I have been on the Mexico cruise and enjoyed it very much. Was one of the best cruises we have been on.
4. We book through Cruises Only out of Orlando, we always get a discounted rate.
5. We have been on 7 cruises and they have all been on Carnival. We have 2 children also and they have been on 4 cruises with us. They really enjoyed the trips.
6. It is perfectly safe to get off the ship with your daughters. Cabo San Lucas is beautiful.
7. We prefer ocean view, you never know what it is like outside when you are in an inside cabin. You can't see if it is raining or whatever until you go outside.